I also had your symptoms. Additional symptom was shortness of breath with little exertion. I had a pulminary test at our local hospital and was diagnosed with COPD (Chronic Obstructive Pulminary Disease). The short of it is I do not exhale enough used air from my lungs to inhale enough fresh air. I was put on a Combivent inhaler 4 times a day. This inhaler has side effects. I have reduced it's use to 3 times a day and none in the evening. Suggest it to your doctor to have the test done.